Apparatus for forming paper between a forming wire and felt



June 20, 1967 J. B. GRAHAM 3,326,745

APPARATUS FOR FORMING PAPER BETWEEN A FORMING WIRE AND FELT Fild Dec. 4.1964 2 Sheets-Sheet June 20, 1967 J. B. GRAHAM 3,326,745

APPARATUS FOR FORMING PAPER BETWEEN A FORMING WIRE AND FELT Filed Dec.4. 1964 z Sheets-Sheet 2 United States Patent 3,326,745 APPARATUS FORFORMING PAPER BETWEEN A FORMING WIRE AND FELT John B. Graham, Neenah,Wis., assignor to Kimberly- Clark Corporation, Neenah, Wis., acorporation of Delaware Filed Dec. 4, 1964, Ser. No. 416,078 3 Claims.(Cl. 162-313) ABSTRACT OF THE DISCLOSURE Paper forming apparatusincluding a movable endless felt and a movable endless foraminousforming wire so disposed that the wire and felt provide a taperingcavity between them into which paper stock is discharged, with asupporting shoe being provided for the portion of the felt forming oneside of the tapering cavity to prevent undue flexing of the felt. Thesupporting shoe may be either in the form of a fiat backing plate or aplate having a convex external surface of gradually decreasing radius.

i The present invention relates generally to papermaking machines andmore particularly to stock inlet arrangements for such machines.

It has previously been proposed that formation of a paper web may takeplace between a foraminous forming fabric and a felt, with the formingfabric and felt being carried by two adjacent turning rolls, thearrangement being such that the forming fabric and felt are broughtsubstantially into contact along web formation areas thereof lying alongone or both of these rolls. After dewatering in the formation areas, theformed web follows and is carried by the felt, and subsequent dewateringand transference to steam heated driers occurs as the web travels withthe felt. Such arrangements are disclosed in the co-pending applicationof C. A. Lee and C. A. Lamb, Ser. No. 161,058, filed Dec. 21, 1961, nowPatent No. 3,224,928.

It is an object of the present invention to provide an improved form ofthis general type of arrangement which is particularly adapted forforming heavyweight sheets at increased speed of production and hasincreased web dewatering capabilities for such sheets.

Briefly stated, the present invention includes an inlet arrangement fora papermaking machine which provides a tapering forming section betweena forming fabric or wire and a felt for preliminary dewatering action onthe web being formed prior to the passage of the forming fabric and feltaround a curved section, such as a turning roll, on which centrifugalforce and a pressure between forming fabric and felt due to thecurvature are exerted for intensive web dewatering action.

The invention consists of the novel constructions, arrangements anddevices to be hereinafter described and claimed for carrying out theabove stated objects, and such other objects, as will be apparent fromthe following description of preferred forms of the invention,illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic fragmentary illustration of the wet end of apapermaking machine including the improved stock inlet construction ofthe invention;

FIG. 1A is a fragmentary illustration on an enlarged scale of the stockinlet construction of the invention; and

FIGS. 2 and 3 are fragmentary illustrations of modified stock inletconstructions of the invention.

Like characters of reference designate like parts in the several views.

Referring now to FIG. 1 of the drawings, the embodiment of the inventiontherein illustrated may be seen. to comprise a loop of web formingfabric or wire which is disposed about rolls 11, 12, 13, 14, 15, 16, 17and 18.

The fabric 10 is a conventional paper web forming fabric for use inFourdrinier machines made up of interwoven warp and shute strands forproviding drainage openings there'between through which water may drainfrom dilute paper stock applied on the fabric. The strands may be eithermetal or may be of synthetic material in accordance with well knownpractice. The roll 12 may be termed a couch roll, since it is at thispoint that the paper web formed in the machine is removed from thefabric 10 as will hereafter appear; and the rolls 11, 13, 16, 17 and 18are simple turning rolls. The roll 13 may be used as a stretch roll withsuitable conventional mechanism (not shown) for simultaneouslyadjustably moving both ends of the roll for maintaining the fabric 10taut about the rolls. The roll is a conventional guide roll having oneend fixed and the other movable, and any suitable conventional apparatus(not shown) may be connected with the movable end of the roll 15 so thatthe roll functions to maintain the fabric loop traveling insubstantially the same path about the rolls supporting the fabric. Oneor more of the fabric supporting rolls, such as, for example,

the roll 11, may be driven for the purpose of driving the fabric 10 sothat it travels in the direction indicated by the arrow A.

An upper loop of fabric 19 is disposed about rolls 20, 21, 22, 23, 24,25, 26, 27, 28, 29, 30, 31, 32, and 33, in addition to the roll 11. Thefabric 19 is one that absorbs water to a greater extent than does theusual water draining paper web forming fabric. The fabric 19 may, forexample, be a conventional papermakers top felt.

The rolls 27 and 29 are pressure rolls each of which has a pressure nipwith a steam heated Yankee drier drum 34. The roll 29 may, for example,have a perforate periphery, and a suction gland 35 may be disposedwithin the roll 29 adjacent to its nip with the drum 34. All of a theother rolls supporting the loop of fabric 19 may have imperforate outersurfaces. The roll 22 is a conventional guide roll having one end fixedand the other end movable under the control of any suitable controlmechanism (not shown) for maintaining the fabric 19 traveling in apredetermined path about the rolls supporting the fabric. The roll 24 isa conventional stretch roll having both ends simultaneously adjustablymovable by suitable adjusting mechanism (not shown) for maintaining thefabric 19 taut about the supporting rolls. The roll 32 may constituteone roll of a main press 36 which also includes another roll 37 having apressure nip with the roll 32. The roll 37 has a perforate outersurface, and a suction gland 38 is disposed within the roll 37 adjacentto the nip of the rolls 32 and 37. The roll 33 is located adjacent tothe roll 12 to have a'slight pressure nip with the roll 12 so that thepaper web transfers from the fabric 10 on to the fabric 19 as the fabric19 leaves the couch roll 12.

An endless bottom felt 39 also passes between rolls 32 and 37. The felt39 is held in looped form by means of supporting rolls 4t), 41, 42, 43,44, 45 and 46. The roll 46 constitutes on roll of wringer 47 whichincludes also a roll 48 having a pressure nip with the roll 46. The roll41 is a conventional stretch roll having both ends simultaneouslyadjustably movable by suitable adjusting mechanism (not shown) formaintaining the bottom felt 39 taut about its supporting rolls. The roll44 is a conventional guide roll having one end fixed and the other endmovable under the control of any suitable control mechanism (not shown)for maintaining the felt 39 traveling in a predetermined path about therolls supporting the fabric. The others of the rolls 40 to 46 are simpleturning rolls.

It will be observed that the rolls 11 and 18 are positioned with respectto each other so as to provide a stretch 102 of the fabric 10 which issubstantially vertical. The roll 20 is so positioned with respect to theroll 11 as to provide a stretch 19z of the fabric 19 which lies slightlyoff vertical so that a tapered cavity 49 is formed between the fabricstretches 191 and 192. A flat backing plate 50 is disposed between therolls 11 and 20 behind the fabric stretch 191, as illustrated. A stockinlet 51 is provided for directing paper stock into the cavity 49, andthis inlet may comprise simply a pair of parallel plates 52 and 53terminating within the cavity 49. The plates 52 and 53 may be positionedinch to inch apart and may be 12 inches to 20 inches in length, forexample. More details of a stock inlet of this type which provides finescale turbulence in the stock may be obtained from the co-pendingapplication of David W. Appel et al., Ser. No. 278,521, filed May 2,1963 (now abandoned).

In operation, the forming fabric or wire 10, the top felt 19 and thebottom felt 39 are respectively driven in the directions indicated bythe arrows A, B and C by any suitable ones of the supporting rolls.Paper stock flows through the inlet 51 and between the parallel plates52 and 53 into the cavity 49; and dewatering of the stock begins withinthe cavity 49, the water moving outwardly through the interstices in thefabric 10. Dewatering continues as the stock moves downwardly in thecavity 49 along with the fabrics and 19 and also continues as thefabrics travel around the roll 11.

The pressure between the fabric 10 and felt 19 is increased as thefabric and felt travel around the roll 11, and this pressure increasesthe dewatering action of the stock which by the time it reaches the roll11 from the ends of the plates 52 and 53, is dewatered to some extent.The magnitude of this pressure varies with both the tension on the wire10 and also the radius of curvature of the roll 11, the pressureincreasing with increased wire tension and decreased roll radius. Thecentrifugal force on the water within the stock also is effective indewatering the stock as it passes around the roll 11, as will beunderstood.

The paper web passes from the roll 11 to the rolls 12 and 33, and atthis point it leaves the forming fabric 10 and travels on the under sideof the felt 19 to the main press 36. The main press together with thebottom felt 39 further dewater the web, and the web travels along withthe felt to the pressure roll 29 and transfers at this point to theYankee drier 34 for drying and subsequent reeling.

The backing plate 51 is preferably provided behind the felt 19 in Viewof the fact that the felt 19 is general ly more elastic than the formingwire 10 and also in view of the fact that a less tension of 10 to poundsper lineal inch, for example, is maintained on the felt, as compared tothe tension on the wire 10 of to 35 pounds per lineal inch, for example.The backing plate thus prevents bowing of the felt 19.

The provision of the tapered cavity 49 prior to the roll 11 providespreliminary dewatering of the stock prior to the high pressures andcentrifugal forces effective as the fabric 10 and felt 19 pass aroundthe roll 11. The illustrated arrangement thus is particularly suitablefor heavy basis weight webs. The rate of closure of the forming fabric10 with respect to the felt 19 in the vicinity of the cavity 49 can,incidentally, be controlled by ad justing the position of the roll 18 toprovide optimum operating conditions for various basis weight webs. Itwill be obvious also that the length of the cavity 49 can be increasedby moving the roll 18 and inlet 51 away from the roll 11 to therebyincrease the drainage length of the cavity 49 prior to the roll 11 forheavier basis Weight sheets. Obviously, if it is desired to increase thepressure of the wire 10 on the felt 19 and the centrifugal force on theweb as it passes around the roll 11 for increased dewatering action, theroll 11 may be decreased in radius.

Advantageously, the tapered cavity 49 provides a gradual closure betweenthe wire 10 and the felt 19, before the wire and felt completely closearound the roll 11, and allows dewatering and drainage from the web totake place without rejection of the stock, particularly the highconsistency stocks for heavy basis weight webs, out from the nip of thewire and felt on the roll 11. The 21"- rangement provides a long,gradually closing forming area defined by the fabric 10 and felt 19 onthe sides of the cavity 49 obviating the necessity for a large diameterforming roll 11.

The paper machine inlet arrangement illustrated in FIG. 2 is basicallysimilar to that shown in FIGS. 1 and 1A, except that a rigid plate 54has been substituted for the backing plate 50 and turning roll 11. Theplate 54 iS flat from one end 54a to a mid-line 54b and is curved on aradius R from the mid-line 54b to the other end 540. Rolls 55 and 56respectively support the wire 10a and felt 19a so as to provide thetapered cavity 49a extending from the rolls 55 and 56 to the mid-line541) at which the felt and wire come together, and a supporting roll 57is provided adjacent the end 54c of the plate 54 and between the plate54 and rolls 12a and 33a that correspond with rolls 12 and 33. It willbe understood that other rolls, such as rolls corresponding to rolls 13to 17 and rolls 21 to 32 support the forming fabric 10a and felt 19a inlooped form as in the first described embodiment. Dewatering of thesheet takes place within the tapered cavity 49a, and increased pressurebetween the fabric 10a and felt 19a and centrifugal force on the web foradditional dewatering take place as the felt and fabric pass around therounded part of the plate 54, similarly to the dewatering effect in thetapered cavity 49 and around the roll 11 in the first describedembodiment.

The papermaking machine inlet arrangement illustrated in FIG. 3 issubstantially the same as that shown in FIG. 2, except that adifferently shaped plate 58 has been substituted for the plate 54. Theforming fabric 10b is supported by the roll 55b and travels around theplate 58 and roll 57b to the rolls 12b and 33b corresponding to therolls 12 and 33 and the rolls 12a and 33a. The felt 19b travels aroundthe roll 56b and around the plate 58 also to the rolls 57b, 33b and 12b.The inlet 51b, which is similar to the inlets 51 and 51a, dischargesstock into a tapered cavity 49b provided between the forming fabric 10band felt 19b.

The plate 58 has a plane portion between one end 58a and a center line58b extending longitudinally of the plate 58 which corresponds to theportion of the plate 54 between the end 54a and line 54b, and the fabric10b and felt 19b come together substantially along the line 58b. Thefabric 10b and felt 19b provide the tapering cavity 49b between theplate end 58a and the line 58b, and the initial dewatering of the stockoccurs in this cavity. The plate 58, however, differs from the plate 54in that, between the lines 58b and the end 58c, the plate 58 is providedwith a changing curvature. The curvature of the plate 58 close to theline 58b is relatively slight; however, the radius of curvature of theplate 58 as it approaches the roll 57b becomes less and less. The radiusof curvature along the longitudinal line 58a, for example, is muchgreater than is the radius of curvature along the longitudinal line 58::on the plate 58.

The plate 58 with this gradually decreasing radius of curvature providesa greater and greater pressure between the forming fabric 10b and felt19b as the fabric and felt approach the roll 57b and also provides moreand more centrifugal force on the moisture in the web being formedbetween the fabric 10b and felt 19b as the web approaches the roll 57b.This increased pressure is in view of the relation mentioned above,namely, that the pressure between wire and felt increases with decreasedradius of curvature. The arrangement illustrated in FIG. 3 isparticularly suitable for very heavy basis weight webs and is such thatrejection of stock back toward the inlet is less likely to occur withvery heavy basis weight webs in view of the fact that, as a sheet isdewatered to a greater and greater extent, it is more able to withstandincreased pressure between forming fabric and felt and increasedcentrifugal forces. Also, utilizing the arrangement of FIG. 3, greaterforming speed and a drier sheet may be expected with such heavy basisweight webs than if a constant radius is utilized, such as, for example,the radius R of the plate 54b in FIG. 2.

I wish it to be understood that the invention is not to be limited tothe specific constructions, arrangements and devices shown anddescribed, except only insofar as the claims may be so limited, as itwill be understood to those skilled in the art that changes may be madewithout departing from the principles of the invention.

What is claimed is:

1. In a paper web forming machine, an endless felt, means for moving andsupporting said felt and including a roll about which the felt moves,and endless paper web forming fabric having interstices therethrough fordraining paper stock deposited thereon, means for moving and supportingsaid fabric so that the fabric also extends around said roll on top ofthe felt, said supporting means for said fabric and felt including apair of rolls one of which supports the fabric and the other of whichsupports the felt and which are so spaced and positioned that the fabricand felt form a tapering cavity between them extending from these rollsto said first named roll, a paper stock inlet for discharging stock intosaid tapering cavity, and a flat backing plate disposed within said feltand backing the portion of the felt that extends from said first namedroll to one of said pair of rolls for preventing substantial bowing ofthe felt under the action of the paper stock discharged into saidcavity.

2. In a paper web forming machine, an endless felt, means for moving andsupporting said felt and including a plate having a convex externalsurface about which the felt moves, and endless paper web forming fabrichaving interstices therethrough for draining paper stock disposedthereon, means for moving and supporting said fabric so that the fabricalso extends around said convex surface on top of the felt, saidsupporting means for said fabric and felt being so arranged that thefabric and felt form a tapering cavity between them which extends tosaid convex surface, and a paper stock inlet for discharging stock intosaid tapering cavity, said convex surface gradually decreasing in radiusof curvature in the direction of movement of said fabric and felt aboutsaid surface.

3. In a paper web forming machine, an endless felt, means for moving andsupporting said felt and including a plate having a plane externalsurface joining a convex curved external surface and positioned so thatthe felt moves on said plane surface and from thence around said convexsurface, an endless paper web forming fabric having interstices fordraining paper stock deposited thereon, means for moving and supportingsaid fabric so that the fabric also extends around said convex surfaceon top of the felt and travels with the felt and forms a tapering cavitybetween it and the portion of the felt on said plane surface, and apaper stock inlet for discharging stock into said tapering cavity.

References Cited UNITED STATES PATENTS 1,927,360 9/1933 Edge 162317 X2,977,277 3/1961 Kelly 162-403 3,132,990 5/1964 Trufitt 162317 3,224,92812/1965 Lee et al. 162-203 X FOREIGN PATENTS 4,182 1881 Great Britain.

S. LEON BASHORE, Primary Examiner.

DONALL H. SYLVESTER, Examiner.

J. NEWSOME, Assistant Examiner.

1. IN A PAPER WEB FORMING MACHINE, AN ENDLESS FELT, MEANS FOR MOVING ANDSUPPORTING SAID FELT AND INCLUDING A ROLL ABOUT WHICH THE FELT MOVES,AND ENDLESS PAPER WEB FORMING FABRIC HAVING INTERSTICES THERETHROUGH FORDRAINING PAPER STOCK DEPOSITED THEREON, MEANS FOR MOVING AND SUPPORTINGSAID FABRIC SO THAT THE FABRIC ALSO EXTENDS AROUND SAID ROLL ON TOP OFTHE FELT, SAID SUPPORTING MEANS FOR SAID FABIRC AND FELT INCLUDING APAIR OF ROLLS ONE OF WHICH SUPPORTS THE FABRIC AND THE OTHER OF WHICHSUPPORTS THE FELT AND WHICH ARE SO SPACED AND POSITINED THAT THE FABRICAND FELT FORM A TAPERING CAVITY BETWEEN THEM EXTNEDING FROM THESE ROLLSTO SAID FIRST NAMED ROLL, A PAPER STOCK INLET FOR DISCHARGING STOCK INTOSAID TAPERING CAVITY, AND A FLAT BACKING PLATE DISPOSED WITHIN SAID FELTAND BACKING THE PORTION OF THE FELT THAT EXTENDS FROM SAID FIRST NAMEDROLL TO ONE OF SAID PAIR OF ROLLS FOR PREVENTING SUBSTANTIAL BOWING OFTHE FELT UNDER THE ACTION OF THE PAPER STOCK DISCHARGED INTO SAIDCAVITY.